Suspension system for a vehicle

ABSTRACT

A suspension travel adjustment mechanism comprises a housing containing a fluid, and a shaft extending through the housing. A piston is coupled to the shaft to define an upper chamber and a lower chamber within the housing. A fluid passageway extends between the upper chamber and the lower chamber. A mechanism is used for selectively opening and closing the fluid passageway from outside of the housing permit the fluid to flow between the upper chamber and the lower chamber when the fluid passageway is opened.

CROSS REFERENCES TO RELATED APPLICATIONS

This application is a continuation in part application and claims thebenefit of U.S. application Ser. No. 10/120,474, filed Apr. 10, 2002,now U.S. Pat. No. 6,669,219 the complete disclosure of which is hereinincorporated by reference.

BACKGROUND OF THE INVENTION

This invention relates generally to the field of two wheel vehicles.More specifically, the invention relates to two wheeled vehiclesuspension systems and releasable wheel clamping systems.

The use of front and full suspensions in two wheeled vehicles has becomewidespread. For example, motorcycles have long had suspension systems.In recent years, front and full suspension systems in mountain bikeshave become almost standard equipment. One pioneering effort to createsuch suspension systems was spearheaded by Rockshox, Inc. as describedgenerally in U.S. Pat. Nos. 4,971,344; 5,186,481; 5,456,480; and5,580,075, the complete disclosures of which are herein incorporated byreference. Another successful suspension system for a two wheeledvehicle is described in copending U.S. applications Ser. Nos. 09/502,272and 09/502,746, both filed Feb. 11, 2000, the complete disclosures ofwhich are herein incorporated by reference.

This invention provides another type of suspension for two wheeledvehicles. The invention also relates to the releasable coupling of awheel to the fork of a two wheeled vehicle.

SUMMARY OF THE INVENTION

In one embodiment, the invention provides a telescoping fork for thefront wheel of a two wheeled vehicle. The fork comprises a pair of outertubes that each have a top end and a bottom end. An upper structuralmember and a lower structural member are employed to connect the outertubes, with the lower structural member being spaced below the upperstructural member. Further, each outer tube tapers outwardly, bothexternally and internally, in a direction both from the top end and thebottom end toward the lower structural member. With such aconfiguration, the strength of the outer tubes is increased withoutsignificantly increasing the weight of the fork.

In one aspect, the lower structural member is welded to the outer tubes,and steering bearings are coupled between the upper structural memberand the lower structural member. With this configuration, the steeringbearings may be used to attach the fork to a vehicle frame. In anotheraspect, the lower structural member may have a hollow box sectionalshape.

In one particular arrangement, the fork further includes a pair of innertubes that are disposed to slide within the pair of outer tubes. Theinner tubes each have a bottom end and a top end, and the bottom ends ofthe inner tubes extend out of the bottom ends of the outer tubes. In oneoption, a single bushing may be disposed between each outer tube andeach inner tube. The bushings may be located at the bottom ends of theouter tubes and have a length that is longer than a diameter of theinner tube. The use of such a bushing helps maintain an oil layerbetween the bushing and the inner tube.

In another particular aspect, the fork may include a bracket disposed atthe bottom end of each inner tube. The brackets are employed to clamp afront wheel axle to the inner tubes. Optionally, at least one of thebrackets may have a mount for receiving a disk brake caliper.

Another feature of the fork is the use of a handle bar clamping devicethat is coupled to the upper structural member. In this way, a handlebar may be coupled to the fork.

One particular embodiment of the invention is an adjustable fluiddamping system. The fluid damping system may comprise a damper tubeextending upward from the top end of the inner tube (and in some casesthe damper tube may simply be an extension of the inner tube), a hollowdamper rod coupled to the top end of the outer tube and extending intothe damper tube, and a damper piston valve coupled to the damper rodthat seals against the damper tube. The fluid clamping system mayfurther include a lock tube that is disposed within the damper rod. Thedamper rod may have at least one upper orifice and one lower orifice,and the lock tube may be rotatable from the top end of the outer tube toclose the lower orifice to limit the amount of extension of the lowertube out of the upper tube. In this way, the amount of extension of thesuspension system may easily be adjusted from outside of the fluiddamping system. For instance, when ready to climb a steep hill, therider may quickly adjust the lock tube by turning a knob to limit theamount of extension during climbing.

In one particular aspect, this is accomplished by configuring the damperpiston valve as a one-way valve that permits fluid flow in an upwarddirection upon compression of the inner tube into the outer tube.Further, a sleeve may be disposed over a top portion of the damper rodand the lock tube. The sleeve is configured to close the upper orificeas the upper tube extends relative to the lower tube, such that furtherextension is prevented if the lower orifice is closed by the lock tube.Conveniently, a stop may be positioned between the top of the outer tubeand the top of the inner tube to stop compression of the inner tube intothe outer tube.

In one alternative aspect, the inner tube may have a closed end orsection, and a sealed piston may be disposed inside the inner tube. Thepiston may be connected to a rod that extends and attaches to the topend of the outer tube. Further, a gas may be held within the inner tubeand is compressed by the piston to provide a damping effect. Optionally,a spring may be disposed between the bottom end of the inner tube andthe piston to form a biasing effect. The rod may also be hollow topermit the gas pressure in the inner tube to be adjusted by a valve atthe top end of the outer tube.

In a further embodiment, the invention provides a releasable clampsystem for clamping a wheel axle of wheel to a two-wheeled vehicle. Theclamp system comprises a frame member that defines a shape that isconfigured to receive a portion of the wheel axle. A cover plate ispivotally attached to the frame member and is configured to receiveanother portion of the wheel axle. In this way, the cover plate may bemoved to a closed position where the frame member and the cover plategenerally encompass and clamp the wheel axle, and to an open positionwhere the wheel axle may be removed. A lever is pivotally attached tothe cover plate, and a hook member is pivotally attached to the lever.The hook member is configured to hook onto the frame member and bepulled by the lever to secure the cover plate to the frame member whenthe cover plate is moved to the closed position.

In one aspect, the cover plate may be pivotally attached to a top end ofthe frame member to permit the wheel axle to be vertically released fromthe frame member. In another aspect, the inner surfaces of the framemember and the cover plate that are adjacent the wheel axle are eachsemi-circular in geometry.

In a further aspect, the hook member may be T-shaped, and the framemember may include a shoulder with a slot into which the hook member isreceived. Optionally, the hook member may be constructed of two piecesthat are threadably connected together. In this way, the clamping forceon the wheel axle may be adjusted by rotating the pieces relative toeach other prior to clamping.

In yet another aspect, torsion springs may be provided at pivot pointslocated where the cover plate attaches to the frame member and where thelever attaches to the cover plate. The torsion springs hold the coverplate open when not clamping the wheel axle. Further, a mount may beprovided on the frame member to mount a disk brake caliper to the framemember.

The invention also provides alternative techniques for externallyadjusting the amount of travel of a telescoping suspension system. Suchtelescoping suspension systems may be constructed of a telescoping tubearrangement where two tubes slide relative to each other. To adjust theamount of travel of the telescoping tube arrangement, a traveladjustment mechanism may be used. The travel adjustment mechanism may beconstructed of a tube member having a closed end and an open top end. Aseal head is disposed at the top end of the tube member, and a hollowrod unit passes through the seal head. The rod unit has a top end and abottom end, and a piston is coupled to the bottom end of the hollow rodso as to be disposed in the tube member. The travel adjustment mechanismis operably coupled rod unit and is operable from outside of thetelescoping tube arrangement to adjust the effective length of the rodunit. In so doing, the amount of extension of the telescoping tubearrangement is adjusted. More specifically, by adjusting the length ofthe rod unit, the point at which the piston engages the seal head isvaried. As such, the amount of extension of telescoping tube arrangementis limited to thereby limit the total suspension travel.

Conveniently, the travel adjustment mechanism may include an adjustmentknob that is rotatable to adjust the effective length of the rod unit.The adjustment knob may be located outside of the telescoping tubearrangement so that the adjustment may easily occur from outside of thesuspension system.

The telescoping tube arrangement may comprise an outer tube and an innertube that is slidable within the inner tube. The telescoping tubearrangement may be configured so that the wheel axle is operably coupledto either the outer tube or the inner tube. As such. The tube membercontaining the piston may be operably coupled to either the inner tubeor the outer tube. Also, the travel adjustment mechanism may be coupledto either the outer tube or the inner tube by a top cap, with theadjustment knob extending out of the top cap.

In one aspect, a biasing material is disposed within the tube memberbetween the closed end and the piston. This biasing material maycomprise a spring or some type of fluid, such as a gas. In this way,telescoping tube arrangement functions as a spring type suspension.

In a specific aspect, the travel adjustment mechanism comprises ahousing containing a pressurized gas, alone or in combination with aliquid, and a first shaft that extends through the housing and that hasa pair of spaced apart orifices. A piston coupled to the first shaftbetween the orifices to define an upper chamber and a lower chamberwithin the housing. The travel adjustment mechanism further includes asecond shaft and a valve that is disposed between the two orifices. Inthis way, the second shaft is movable to open the valve and to permitthe pressurized fluid to flow between the upper chamber and the lowerchamber through the two orifices. With such a configuration, theadjustment knob may be manipulated to move the second shaft within thefirst shaft to open the valve and permit the fluid to flow between thetwo chambers.

Advantageously, the first shaft may have a outer diameter above thepiston that is larger than the outer diameter below the piston so thatwhen the valve is opened, a biasing effect is produced that tends tolengthen the travel adjustment mechanism. Hence, when the knob ismanipulated the telescoping tube arrangement will tend to extend. Tomake the proper adjustment, a downward force may be applied to the forkto compress the telescoping tube arrangement. In so doing, pressurizedgas is transferred from the lower chamber of the housing to the upperchamber. When the proper configuration is reached, the adjustment knobmay be turned in the opposite direction to close the valve and maintainthe telescoping tube arrangement in the same position.

Another feature is that the first shaft may include a tapered seat thatis positioned between the two orifices. The second shaft may alsoinclude a tapered bottom end that engages the tapered seat to form thevalve. In a further aspect, the travel adjustment mechanism, the hollowrod unit and the piston may define a fluid flow passage into the tubemember to permit the pressure within the tube member to be adjusted atthe travel adjustment mechanism. For example, a valve may be provided inthe adjustment knob to permit a pressurized fluid to be input into orexhausted from the tube member.

BRIEF DESCRIPTION OF THE DRAWINGS

FIG. 1 is a front isometric view of a telescoping fork releasablycoupled to a front wheel of a two wheeled vehicle according to theinvention.

FIG. 2 is a more detailed view of a top portion of the fork of FIG. 1.

FIG. 3 is a rear isometric view of the fork of FIG. 1 shown coupled to ahandle bar.

FIG. 4 is a cross-sectional top view of the fork of FIG. 1 taken througha lower structural member.

FIG. 5 is a cross-sectional side view of the fork of FIG. 1

FIG. 6 is a more detailed view of some of the components of the fork ofFIG. 5 showing fluid flow during compression.

FIG. 7 illustrates the components of FIG. 6 showing fluid flow duringextension.

FIG. 8 is a more detailed view of a bushing disposed between an outertube and an inner tube.

FIG. 9 is a more detailed view of a clamp system of the fork of FIG. 1.

FIG. 10 illustrates the clamp system of FIG. 9 in an open position.

FIG. 11 is another view of the clamp system of FIG. 10.

FIG. 12 is a cross sectional side view of the clamp system of FIG. 9.

FIG. 13 is a cross-sectional side view of an alternative fork sectionaccording to the invention.

FIG. 14 is a cross-sectional side view of a further embodiment of a forksection according to the invention.

FIG. 15 is a front view of an alternative embodiment of a suspensionsystem according to the invention.

FIG. 15A is a cross-sectional side vie of the suspension system of FIG.15 taken long lines A—A.

FIG. 16 is a front view of a spring assembly of the suspension system ofFIG. 15.

FIG. 16A is a cross-sectional side view of the spring assembly of FIG.16.

FIG. 16B is a cross-sectional side view of a travel adjustment mechanismof the spring assembly of FIG. 16A.

FIG. 17 is a front view of an alternative suspension system according tothe invention.

FIG. 17A is a cross-sectional side view of the suspension system of FIG.17

DETAILED DESCRIPTION OF THE INVENTION

In one aspect, the invention provides various suspension systems havinga variety of features. One such feature is the use of fork that isconstructed of telescoping outer tubes. The tubes have an inner diameterand an outer diameter that both increases in a direction from the axlemount upward as well as from the top of the fork downward. The maximumamount of taper may occur near where the two tubes are joined togetherby a structural member. For example, the tubes may taper outward from aninner diameter in the range from about 32 mm to about 34 mm and an outerdiameter in the range from about 34 mm to about 38 mm, to an innerdiameter in the range from about 44 mm to about 48 mm and an outerdiameter in the range from about 48 mm to about 52 mm, although otherdimensions are possible. Such a configuration increases the strength ofthe fork without appreciably increasing its weight.

Another feature of the invention is the ability to limit the amount ofextension of the suspension system. This may be done manually fromoutside of the suspension system. For example, such an adjustment may bedone by simply turning a knob. Such a feature is useful when peddlinguphill to keep the front end of the bicycle closer to the ground toprevent tipping backward. When on level or down sloping terrain, thesuspension system may again be adjusted to permit full extension.

A further feature is a releasable clamp system that provides for a quickrelease of the wheel from the fork. By the simple operation of a lever,the wheel may be vertically released from the fork.

Referring now to FIG. 1, one embodiment of a fork 10 of a two-wheeledvehicle will be described. Fork 10 is constructed of a pair of outertubes 12 and 14 that may both be fashioned in a substantially similarmanner. Outer tubes 12 and 14 are coupled together by a lower structuralmember 16 and an upper structural member 18. Outer tubes 12 and 14 maybe constructed of a strong and rigid material, such as steel, aluminum,or the like. Lower structural member 16 may be constructed of a similarmaterial and may be welded to outer tubes 12 and 14. Upper structuralmember 18 may be coupled to tubes 12 and 14 using screws 20 (see alsoFIG. 2) that may be tightened or loosened using an Allen wrench.Alternatively, upper structural member 18 may be welded to tubes 12 and14. Upper structural member 18 also includes a coupling arrangement 22for coupling a handlebar 24 (see FIG. 3) to fork 10. Optionally, thismay be incorporated directly into upper structural member 18.

Coupled between structural members 16 and 18 is a rotatable member 26having steering bearings. Rotatable member 26 is a steering column thatis configured to be coupled to a vehicle frame as is known in the art tocomplete the vehicle.

Extending out of outer tubes 12 and 14 are inner tubes 28 and 30. Innertubes 28 and 30 are slidable within outer tubes 12 and 14 and arecoupled to a clamping system 34, 36 as described hereinafter. As alsodescribed hereinafter, an adjustment knob 78 is at a top end of outertube 12 and may be used to adjust the amount of extension of inner tubes28 and 30 out of outer tubes 12 and 14.

Coupled to inner tubes 28 and 30 are clamp systems 34 and 36 that areeach substantially identical. Clamp systems 34 and 36 are employed tocouple an axle 38 of a wheel 40 to fork 10 and will be described ingreater detail hereinafter.

Lower structural member 16 is shown in cross section in FIG. 4 and has abox sectional shape. Such a shape is useful in that it provides thegreatest amount of rigidity for the least weight.

As best shown in FIG. 5, outer tube 12 (as well as outer tube 14) tapersoutward, both externally and internally, from near its bottom end 42 toa location 44 where tube 12 is coupled to lower structural member 16(see FIG. 1). Outer tube 12 also tapers outward, both externally andinternally from its top end to location 44. This configuration permitsouter tube 12 to have an inner diameter at bottom end 42 that isslightly larger than inner tube 28, and to have a greater inner diameterat location 44 where greater stresses occur. In this way, the overallstrength of fork 10 is increased. Further, by also increasing the outerdiameter of tube 12, a relatively small wall thickness may be maintainedto reduce the weight of fork 10.

Referring to FIGS. 5–7, construction and operation of a damping system50 will be described. Damping system 50 is constructed out of outer tube12 and inner tube 28 that slides within outer tube 12. Inner tube 28 iscoupled to a damper tube 52 that has threads 54 that thread intocorresponding threads of inner tube 28. Damper tube 52 has a closedbottom end 56 and a top end having a seal head 58. In some cases, dampertube 52 may simply be an integrally formed extension of inner tube 28.Extending down from seal head 58 and into damper tube 52 is an outersleeve 60. An O-ring 62 is coupled to the bottom end of outer sleeve 60.Extending through outer sleeve 60 and seal head 58 is a hollow damperrod 64. An O-ring 65 provides a seal between seal head 58 and damper rod64. Coupled to a bottom end of damper rod 64 by a nut 63 is a dampervalve piston 66 that is configured as a one-way valve. Piston valve 66also divides damper tube 52 into a lower oil chamber 68 and an upper oilchamber 70, although other fluids may be used as well. Piston valve 66includes a flexible valve washer 71 that is shown in an open position inFIG. 6 during compression of damping system 50 to permit fluid flowthrough a valve 72. As shown in FIG. 7, washer 71 is an a closedposition during extension of damping system 50 to prevent flow throughorifice 72. Disposed above piston valve 66 is a bottom extension orifice74 (although more than one may be used). Also, positioned above bottomorifice 74 is one or more top extension orifices 75.

Coupled to a top end of damper tube 64 is a top cap 76 that in turn iscoupled to outer tube 12 (see FIG. 5). A bottom out pad 79 is coupled totop cap 76 and may comprise an O-ring. Pad 79 is used to soften theimpact and protect top cap 76 if damping system 50 bottoms out, i.e.,when seal head 58 reaches top cap 76. Optionally, pad 79 may be providedanywhere along damper rod 64, and damper rod 64 may be provided with ashoulder to hold pad 79 in place. Disposed on top of top cap 76 is anadjuster knob 78 that in turn is coupled to a lock tube 80. In turn,lock tube 80 is adjacent to and coaxially disposed within damper rod 64.Knob 78 is rotatable to rotate lock tube within damper rod 64. Lock tube80 also includes a set of upper orifices 82 that are aligned with toporifices 75 of damper rod 64. Orifices are preferably configured asslots so that when knob 78 is rotated, a fluid flow path remains throughdamper rod 64 and lock tube 80.

Lock tube 80 also includes a lower orifice 84 that is aligned withbottom extension orifice 74 of damper rod 64. Upon rotation of knob 78,orifice 84 may be rotated out of alignment with orifice 74 so that fluidflow between upper oil chamber 70 and the interior of damper rod 64through orifice 74 is prevented when orifice 75 passes above O-ring 62.Damper rod 64 also includes an opening 86 at its bottom end that permitsfluid to flow both into and out of damper rod 64.

By utilizing lock tube 80, damper system 50 may be operated in one oftwo modes simply by rotating knob 78. In FIGS. 6 and 7, damper system 50is shown in an unrestricted mode where orifice 84 is aligned withorifice 74. In FIG. 6, damper system 50 is being compressed, such aswhen a rider encounters a bump. In such cases, inner tube 28 slides intoouter tube 12. Since damper tube 52 is coupled to inner tube 28 and topcap 76 is coupled to outer tube 12, damper rod 64 and lock tube 80 movefurther into damper tube 52. In so doing, the fluid within lower chamber68 moves upwardly through valve orifice 72 and into upper chamber 70, aswell as upwardly through damper rod 64 as shown by the flow lines inFIG. 6. The fluid flowing upward through damper rod 64 may exit intoupper chamber 70 through orifices 74 or 75 as shown. The “stiffness” ofdamping system 50 during compression may be varied by varying theflexibility of valve washer 71, as well as the number and/or size of theexit orifices.

During extension (as shown in FIG. 7), valve washer 71 is forceddownward to close orifice 72. As such, fluid in upper chamber 70 mayonly pass into lower chamber 68 through damper rod 64 as shown by theflow lines. If the amount of extension becomes so great that orifices 75move within outer sleeve 60, fluid in upper chamber 70 may still passinto lower chamber 68 through orifices 74 and 84.

Damper system 50 may be placed into an extension limiting mode by simplyturning knob 78 until orifice 84 is out of alignment with orifice 74. Inthis configuration, lock tube 80 prevents fluid flow through orifice 74and into damper rod 64. Hence, once damper system 50 extends sufficientto move orifice 75 beyond O-ring 62, outer sleeve 60 prevents fluid flowfrom upper chamber 70 and into damper rod 64 via orifice 75. Moreover,because orifice 74 also is closed, none of the fluid in upper chamber 70may pass into lower chamber 68, thus stopping further extension.

Hence, a rider may quickly and easily control the amount of extensionsimply by rotating knob 78 which is easily accessible since it isoutside of outer tube 12. For example, when climbing a hill a rider maywant to keep the front end of the bicycle closer to the ground. To doso, knob 78 may simply be turned to limit the amount of extension. Whenat the top of the hill, knob 78 may be moved back to place dampingsystem 50 in normal operation. As will be appreciated, the amount ofextension may also be controlled by the number, size and/or location oforifices 75. For example, by moving orifices downward, more extensionmay be achieved.

FIG. 8 illustrates the slidable connection between inner tube 28 andouter tube 12. For convenience of illustration, damper system 50 hasbeen removed. Coupled to outer tube 12 is a bushing 90 that is held inplace by a sheath member 92. Also coupled to sheath member 92 is a sealor dust wiper 94 that helps prevent dirt and other particulate frompassing between inner tube 28 and outer tube 12. Bushing 90 isconfigured to maintain a layer of oil between itself and inner tube 28during compression and expansion This is accomplished by using only asingle bushing so that edges do not exist between multiple bushings.Further, bushing 90 has a length that is longer than the diameter ofinner tube 28. This length also helps to maintain the oil layer.

Referring now to FIGS. 9–12, clamp systems 34 and 36 will be describedin greater detail. Clamp systems 34 and 36 are constructed of identicalcomponents and will each be described using the same reference numerals.Clamp system 34 is constructed of a frame member 100 that is coupled toinner tube 28. Frame member 100 has an inner surface 102 for receivingwheel axle 38 and may be approximately semi-circular in shape, althoughother shapes are possible. Pivotally attached to frame member 100 by apivot pin 104 is a cover plate 106 that also has an inner surface 108for receiving the other half of wheel axle 38. As such, inner surface108 may also be approximately semi-circular. Pivotally coupled to coverplate 106 by a pivot pin 110 is a lever 112, and pivotally coupled tolever 112 by a pivot pin 114 is a hook member 116. Hook member 116 isconstructed of a housing 118 and a hook 120 that is T-shaped. Hook 120is threadably connected to housing 118 to permit the distance betweenhook 120 and lever 112 to be adjusted.

Frame member 100 includes a shoulder 122 having a slot 124 for receivinghook 120 when clamping wheel axle 38 to frame member 100. In use, wheel40 (see FIG. 1) may be coupled to inner tube 28 by placing clamp system34 in an open position as shown in FIGS. 10 and 11. Although not shown,torsion springs may be provided about pivot pins 104 and 110 to holdclamp system 34 in the open position. Wheel axle 38 may then be movedvertically up and placed adjacent inner surface 102. This is madepossible by locating cover plate 106 at the top end of inner surface102. Lever 112 may then be operated to pivot cover plate 106 about theother half of wheel axle 38 and to place hook 120 into slot 124 so thatthe end of hook is beyond shoulder 122. Lever 112 is then rotated untilpivot pin 114 moves to an over center position (i.e., past a linepassing between pin 110 and hook 120) and locks cover plate 106 in placewhere wheel axle 38 is clamped in place by surfaces 102 and 108 as shownin FIG. 12. To adjust the clamping force, hook 120 may be screwedfurther into or out of housing 118. When ready to remove wheel 40, lever112 is simply pulled and hook 120 is removed from slot 124. A similarprocess is used to operate clamp system 36.

Also coupled to frame member 100 is a mount 128 that may be employed tomount a disc brake caliper to clamp system 34. Such a disc brake calipermay be similar to those known in the art, e.g., as defined by the G-3Shimano disc brake standard.

Fork 10 may be modified to include other types of damping systems. Twosuch examples are illustrated in FIGS. 13 and 14. For convenience ofdiscussion, the elements in FIGS. 13 and 14 that are similar to thosedescribed in connection with fork 10 will be described using the samereference numerals. FIG. 13 illustrates a fork section 200 that isconstructed of an outer tube 12 that may be connected to the outer tubeof another fork section. For example, a fork may be constructed of forksection 200 that is coupled to the outer tube 12 of a fork section 204(see FIG. 14) in a manner similar to the embodiment illustrated inFIG. 1. Outer tubes 12 may taper outwardly in a manner similar to thatpreviously described.

Slidable within outer tube 12 is inner tube 28 (that is coupled todamper tube 52). In some cases, inner tube 28 and damper tube 52 may bethe same tube. Damper tube 52 includes a closed end 206, and a sealedpiston 208 is slidable within tube 52. A hollow rod 210 is connected topiston 208 at its bottom end and is coupled to the top of outer tube 12at its top end. The top end of outer tube 12 includes a valve region 212into which a valve may be disposed. This valve permits the gas pressurein the space between piston 208 and closed end 206 to be adjusted.

Hence, fork section 200 functions as a damper to dampen a shockexperienced by the two wheeled vehicle. More specifically, as inner tube28 slides into outer tube 12, the gas in damper tube 52 is compressed toprovide a damping effect.

Fork section 204 of FIG. 14 is essentially identical to that of forksection 200 but includes a spring 216 that provides a biasing effect.Hence, fork section 204 may be used in combination with fork section 200to provide a fork having both a damping and biasing effect. Morespecifically, after the fork experiences a shock and is compressed,spring 216 forces inner tube 28 out of outer tube 14.

The invention may also utilize alternative techniques for externallyadjusting the suspension travel. Such adjustments may be made using atravel adjustment mechanism on the spring side of the fork toeffectively shorten a rod that holds the spring piston. In turn, thespring piston stops against the seal head to limit the amount ofextension of the telescoping tubes relative to each other. Hence, as therod is shortened, the amount of total suspension travel is limited.

Such a feature is illustrated generally in FIGS. 15 and 16. Shown inFIGS. 15 and 15A is a telescoping tube arrangement 200 that functions asthe spring side leg of a suspension system. Telescoping tube arrangement200 is constructed of an outer telescoping tube 202 that may be attachedto a lower crown of a fork as described in connection with otherembodiments herein. Slidable within outer tube 202 is an inner tube 204.A bottom end of inner tube 204 is coupled to a drop out assembly 206that is employed to hold the front wheel axle in a manner similar tothat previously described in connection with other embodiments.

Disposed at the top end of outer tube 202 is a top cap 208. Extendingfrom top cap 208 is an adjustment knob 210 that may be rotated to adjustthe amount of travel of inner tube 204 relative to outer tube 202 asdescribed hereinafter. As such, the amount of suspension travel mayeasily be adjusted externally by the user by simply rotating knob 210.

Referring also now to FIGS. 16, 16A and 16B, operation of telescopingtube arrangement 200 will be described in greater detail. As best shownin FIG. 15A, a single bushing 212 is fixed to outer tube 202 andprovides a low friction surface to facilitate sliding of inner tube 204relative to outer tube 202. Conveniently, bushing 212 may be constructedin a manner similar to that described in connection with otherembodiments. Extending from inner tube 204 is a spring tube 214, whichin some cases may be considered to be an extension of inner tube 204.Disposed in spring tube 214 is a piston 216. Spring tube 214 has aclosed bottom end 218 and a top end 220 to which is coupled a seal head222. A biasing material, such as a pressurized gas or a spring mayoptionally be disposed between piston 216 and bottom end 218 to upwardlybias piston 216. Coupled to piston 216 is a spring rod 224. Spring rod224 is hollow and connects piston 216 to top cap 208, which in turn isfixed to the top of outer tube 202.

Disposed between seal head 222 and top cap 208 is a travel adjustmentmechanism 226. As previously mentioned, adjustment of the length oftravel adjustment mechanism 226 is accomplished by rotating adjustmentknob 210 from outside of telescoping tube arrangement 200. As best shownin FIG. 16B, travel adjustment mechanism 226 comprises a housing 228having an open end 230 that is capped with a sealing cover 232 that alsoattaches to spring rod 224. Housing 228 also includes a closed end 234having a sealing arrangement 236. Disposed within housing 228 is apiston 238. Extending upwardly from piston 238 is a first shaft 240 thatattaches to top cap 208. First shaft 240 also extends downwards frompiston 238 and slides within sealing cover 232 and spring rod 224.Conveniently, first shaft 240 and spring rod 224 may be referredtogether as a rod unit. The inner bore of first shaft 240 that extendsabove piston 238 has a diameter that is larger than the diameter of theinner bore that extends below piston 238. Also, formed in first shaft240 are orifices 242 and 244 that are positioned on opposite sides ofpiston 238. Further, first shaft 240 tapers from the top bore to thebottom bore to form a tapered seat 246. Disposed within first shaft 240is a second shaft 248 that extends from adjustment knob 210 down to thetapered seat 246. Second shaft 248 is threadably engaged to top cap 208.Further, disposed within housing 228 is a pressurized gas, optionally incombination with a liquid. Also, it will be appreciated that other typesof valve seats may be used to prevent fluid flow.

With this configuration, when adjustment knob 210 is turned, secondshaft 248 is moved up and down within first shaft 240 depending on thedirection of rotation of adjustment knob 210. The interface betweensecond shaft 248 and the tapered seat 246 defines a valve that preventsfluid flow between an upper chamber 250 and a lower chamber 252 withinhousing 228 when the valve is closed. However, when adjustment knob isrotated to move second shaft 248 upwardly within first shaft 240, aspace forms between the bottom end of second shaft 248 and the taperedseat 246 to open the valve and permit fluid to flow between chambers 250and 252 through orifices 242 and 244. First shaft 240 also has an outerdiameter above piston 238 that is larger than the outer diameter belowpiston 238. Because the first shaft 240 has an outer diameter belowpiston 238 that is smaller than the outer diameter of the first shaft240 above piston 238, the pressurized gas produces an upwardly directedbiasing on piston 238. Hence, when adjustment knob 210 is rotated toopen the valve, outer tube 202 and inner tube 204 will tend to extendrelative to each other. To shorten the length of travel, the user maypress down on the fork to force inner tube 204 within outer tube 202. Inso doing, piston 238 is forced downward and the pressurized gas withinlower chamber 252 passes through orifices 244 and 242 and into upperchamber 250. When adjustment knob 210 is rotated to close the valve,piston 238 generally remains in place. In effect, this shortens thelength of spring rod 224. As such, the amount of travel of inner tube204 out of outer tube 202 is limited because the distance between piston216 and seal head 222 is reduced. As such, if the amount of extension ofinner tube 204 out of outer tube 202 becomes too great, piston 216 willengage seal head 222 to limit the amount of extension. At any time, theamount of extension may be varied by simply rotating adjustment knob 210in the opposite direction, adjusting the position of inner tube 204relative to outer tube 202 and then readjusting knob 210 to close thevalve. In an alternative embodiment, the diameter of first shaft 240 maybe the same both above and below piston 238. In such cases, the housingmay hold an incompressible liquid, such as oil.

Another feature of telescoping tube arrangement 200 is that a fluidchannel may be provided through second shaft 248, through first shaft240, through spring rod 224, through piston 216 and into spring tube214. As such, a valve may be provided within adjustment knob 210 toallow fluids to be introduced into and be withdrawn from spring tube214. In this way, an independent passage runs through the fork leg topermit the pressure of the air spring to be adjusted from outside of thesuspension system and at the same location where the travel adjustmentmay be made. Further, although not shown, it will be appreciated that adamping system could also be incorporated into telescoping tubearrangement in a manner similar to that described herein. As anotheralternative, spring rod 224 could also be configured to move withinspring tube 214.

Hence, telescoping tube arrangement 200 includes a travel adjustmentmechanism that is located on the exterior of the suspension system tocontrol the maximum extended length of inner tube 204 relative to outertube 202. Conveniently, this may be accomplished by utilizing a housinghaving two chambers that are filled with a pressurized fluid. Thetransfer of the fluid between these two chambers changes the effectivelength of the travel adjustment mechanism. Further, using differentinner bore diameters in the travel adjustment mechanism, a biasingeffect is produced that tends to separate the inner tube from the outertube when the adjustment knob is rotated to open the valve.Conveniently, the valve may be configured as a tapered seat to controlthe transfer of fluids between the two chambers.

Referring now to FIGS. 17 and 17A, an alternative telescoping tubearrangement 300 will be described. Telescoping tube arrangement 300 issimilar to arrangement 200 except that the position of the inner andouter tubes have been swapped. Telescoping tube arrangement 300comprises an inner tube 302 that is configured to be coupled to a forkcrown and an outer tube having a connector 306 to permit a wheel axle tobe coupled to outer tube 304. Disposed within outer tube 304 is a springtube 308 that is coupled at its bottom end to outer tube 308. A sealhead 310 is coupled to the top end of spring tube 308. Disposed withinspring tube 308 is a piston 312 that is coupled to a hollow rod 314. Inturn, rod 314 is coupled to a travel adjustment mechanism 316 that maybe constructed essentially identical to travel adjustment mechanism 226.As such, travel adjustment mechanism will not be described in detail.

Coupled to the top end of inner tube 302 is a top cap 316 to whichtravel adjustment mechanism 316 is coupled in a manner similar to thatpreviously described with other embodiments. Extending out of top cap316 is an adjustment knob 318 that may be used to adjust the amount oftravel of the suspension system in a manner similar to that describedwith previous embodiments.

In operation, inner tube 302 slides within outer tube 204. To limit theamount of extension of inner tube 302 out of outer tube 204, adjustmentknob 318 may be used to effectively shorten the length of the rod unitin a manner similar to that previously described. In so doing, thedistance between piston 312 and seal head 310 is adjusted to limit theamount of travel.

The invention has now been described in detail for purposes of clarityand understanding. However, it will be appreciated that certain changesand modifications may be practiced within the scope of the appendedclaims.

1. A suspension system for a vehicle, comprising: a tube member having aclosed end and an open end; a seal head disposed at the open end of thetube member; a rod unit passing through the seal head, wherein the rodunit has a top end and a bottom end; a flange coupled to the bottom endof the rod unit so as to be disposed in the tube member, wherein theflange is configured to come into contact with the seal head to limitextension of the suspension; and a travel adjustment mechanism operablycoupled to the rod unit, wherein the travel adjustment mechanism isoperable to adjust the effective length of the rod unit and therebyadjust the amount of extension of the suspension system; wherein thetravel adjustment mechanism comprises a housing containing anon-compressible fluid, a first shaft extending through the housing anda piston coupled to the first shaft to define an upper chamber and alower chamber within the housing, a passageway past the piston thatconnects the upper chamber and the lower chamber, and a valve that maybe opened to permit the fluid to flow between the upper chamber and thelower chamber through the passageway.
 2. A system as in claim 1, furthercomprising an adjustment knob that is manipulatable to adjust theeffective length of the rod unit.
 3. A system as in claim 1, furthercomprising a telescoping tube arrangement operably coupled to the tubemember, wherein the travel adjustment mechanism is operable control theamount of extension of the telescoping tube arrangement.
 4. A system asin claim 3, wherein the telescoping tube arrangement comprises an outertube having a top end and a bottom end and an inner tube coupled to thetube member, wherein the top end of the outer tube is coupled to thetravel adjustment mechanism with a top cap, and wherein the inner tubeis movable within the outer tube.
 5. A system as in claim 3, wherein thetelescoping tube arrangement comprises an outer tube and an inner tubehaving a top end and a bottom end, wherein the top end of the inner tubeis coupled to the travel adjustment mechanism with a top cap, whereinthe inner tube is movable within the outer tube, and wherein the tubemember is coupled to the outer tube.
 6. A system as in claim 1, furthercomprising a biasing material disposed within the tube member betweenthe closed end and the piston, wherein the biasing material is selectedfrom a group consisting of a spring or a gas.
 7. A system as in claim 1,wherein the non-compressible fluid comprises a pressurize gas, whereinthe travel adjustment mechanism further comprises a pair of spaced apartorifices affording access to the passageway, wherein the piston iscoupled to the first shaft between the orifices, wherein the secondshaft is movable to open the valve and permit the pressured gas to flowbetween the upper chamber and the lower chamber through the twoorifices.
 8. A system as in claim 7, wherein the first shaft has anouter diameter above the piston that is larger than an outer diameterbelow the piston such that when the valve is opened, a biasing effect isproduced to lengthen the travel adjustment mechanism.
 9. A system as inclaim 8, wherein the first shaft includes a tapered seat that ispositioned between the two orifices, and wherein the second shaftincludes a bottom end that engages the tapered seat to form the valve.10. A system as in claim 1, wherein the travel adjustment mechanismextends at least partially outside of the suspension system to permitadjustments to be made from outside of the suspension system.
 11. Asystem as in claim 1, wherein the rod unit is hollow, and wherein thetravel adjustment mechanism, the hollow rod unit and the piston define afluid flow passage into the tube member to permit the pressure withinthe tube member to be adjusted at the travel adjustment mechanism.
 12. Asuspension travel adjustment mechanism, comprising: a housing containinga fluid; a first shaft extending through the housing, the first shafthaving a longitudinal axis and having a pair of longitudinally spacedapart orifices; a piston coupled to the first shaft between the orificesto define an upper chamber and a lower chamber within the housing; asecond shaft; and a valve disposed between the two orifices, wherein thesecond shaft is movable to open the valve and permit the fluid to flowbetween the upper chamber and the lower chamber through the twoorifices.
 13. A mechanism as in claim 12, wherein the fluid comprises apressurized gas, and wherein the first shaft has an outer diameter abovethe piston that is larger than the an outer diameter below the pistonsuch that when the valve is opened, a biasing effect is produced tolengthen the travel adjustment mechanism.
 14. A mechanism as in claim13, wherein the first shaft includes a seat that is positioned betweenthe two orifices, and wherein the second shaft includes a bottom endthat engages the seat to form the valve.
 15. A telescoping suspensionsystem for a vehicle, the system comprising: a telescoping tubearrangement; a tube member operably coupled to the telescoping tubearrangement, the tube member having a closed end and an open end; a sealhead disposed at the open end of the tube member; a rod unit passingthrough the seal head, wherein the rod unit has a top end and a bottomend; a piston coupled to the bottom end of the rod unit so as to bedisposed in the tube member; and a travel adjustment mechanism operablycoupled to the rod unit, wherein the travel adjustment mechanism isoperable from outside of the telescoping tube arrangement to adjust theeffective length of the rod unit thereby adjust the amount of extensionof the telescoping tube arrangement.
 16. A system as in claim 15,wherein the travel adjustment mechanism, the rod unit and the pistondefine a gas flow passage into the tube member from outside of thetelescoping tube arrangement to permit a fluid to be introduced into orwithdrawn from the tube member from outside of the telescoping tubearrangement.
 17. A system as in claim 16, wherein the travel adjustmentmechanism comprises a housing containing at least an amount of apressurized gas, a first shaft extending through the housing and havinga pair of spaced apart orifices, a piston coupled to the first shaftbetween the orifices to define an upper chamber and a lower chamberwithin the housing, a second shaft and a valve disposed between the twoorifices, wherein the second shaft is movable to open the valve andpermit the pressured fluid to flow between the upper chamber and thelower chamber through the two orifices.
 18. A system as in claim 17,wherein the first shaft has an outer diameter above the piston that islarger than the an outer diameter below the piston such that when thevalve is opened, a biasing effect is produced to lengthen the traveladjustment mechanism.
 19. A suspension system for a vehicle, comprising:a tube member having a closed end and an open end; a seal head disposedat the open end of the tube member; a rod unit passing through the sealhead, wherein the rod has a top end and a bottom end; a piston coupledto the bottom end of the hollow rod unit so as to be disposed in thetube member; and a travel adjustment mechanism operably coupled to therod unit, wherein the travel adjustment mechanism is operable to adjustthe position of the effective length of the rod unit and thereby adjustthe amount of extension of the suspension system; a telescoping tubearrangement operably coupled to the tube member, wherein the traveladjustment mechanism is operable control the amount of extension of thetelescoping tube arrangement, wherein the telescoping tube arrangementcomprises an outer tube and an inner tube having a top end and a bottomend, wherein the top end of the inner tube is coupled to the traveladjustment mechanism with a top cap, wherein the inner tube is movablewithin the outer tube, and wherein the tube member is coupled to theouter tube.
 20. A suspension system for a vehicle, comprising: a shockabsorber comprising a rod that controls the extended length of the shockabsorber; and an adjustment mechanism operably coupled to the rod toadjust the effective length of the rod and thereby adjust the amount ofextension of the suspension system, wherein the adjustment mechanismcomprises a housing containing a non-compressible fluid, a shaftextending through the housing and a piston coupled to the shaft todefine an upper chamber and a lower chamber within the housing, apassageway past the piston that connects the upper chamber and the lowerchamber, and a valve that may be opened to permit the fluid to flowbetween the upper chamber and the lower chamber through the passageway.